In　this　study,　Al-Zn-Mg-Cu　alloys　with　high　strength　and　ductility　were　successfully　prepared　by　wire　arc　additive　manufacturing　technology.　Innovatively,　the　effect　of　composite　processing　(heterogeneous　particles　and　heat　treatment)　on　the　microstructure　and　mechanical　properties　of　Al-Zn-Mg-Cu　alloy　arc　additive　manufacturing　deposition　was　studied.　After　composite　processing,　the　grain　morphology　of　the　deposition　was　successfully　transformed　from　coarse　columnar　crystals　to　dense　equiaxed　crystals,　and　the　precipitation　of　nano-precipitated　phases　was　greatly　promoted.　The　influence　of　microstructure　on　mechanical　properties　was　deeply　investigated.　Because　of　the　modification　of　the　microstructure,　the　tensile　strength　of　the　depositions　increased　from　206.8　+/-　14.3　MPa　to　503.6　+/-　10.1　MPa　(horizontal　direction)　and　256.2　+/-　13.1　MPa　to　501.2　+/-　10.0　MPa　(vertical　direction),　and　the　elongation　increased　from　4.1　+/-　0.9　%　increased　to　10.9　+/-　1.0　%　(horizontal　direction)　and　6.6　+/-　0.3　%　to　13.4　+/-　0.3　%　(vertical　direction),　and　the　hardness　was　also　increased　from　117.9　HV　to　197.9　HV.　Finally,　investigations　revealed　that　the　composite　processing　not　only　promotes　the　simultaneous　increase　of　strength　and　elongation,　but　also　greatly　improves　the　anisotropy　of　the　deposition.　Fine　grain　strengthening　is　the　main　mechanism　of　increasing　elongation.　Precipitation　strengthening　is　the　main　mechanism　of　strength　enhancement.　This　research　can　provide　theoretical　guidance　for　improving　the　strength　and　elongation　of　Wire　Arc　Additive　Manufacturing　Al-Zn-Mg-Cu　alloys,　thus　promoting　engineering　applications.